Born in Mount Vernon, Washington,[2] Oshie was raised in Everett, north of Seattle, and was on ice at age five in the Seattle Junior Hockey Association, where he played for 10 years.[3] Following his parents' amicable divorce, he lived in Stanwood with his mother Tina and attended Stanwood High School for his freshman year. In 2002, Oshie moved to Warroad, Minnesota, where his parents were originally from, and lived with his father, Tim, and his father's cousin. He attended Warroad High School,[4] where he was a star player on the hockey team for three seasons, leading the club to two Minnesota State Class A titles in 2003 and 2005. He made the state's All-Tournament Team all three years. With 100 points (37 goals, 63 assists) in 31 games as a senior, he led all Minnesota high school players in scoring. He was subsequently named to 2005 Associated Press and Pioneer Press All-State First Team and was a Minnesota Mr. Hockey Finalist.[5] At the completion of his senior season with the Warriors in 2004–05, he joined the Sioux Falls Stampede of the United States Hockey League (USHL) for 11 games. In the off-season, he was selected 24th overall by the St. Louis Blues in the 2005 NHL Entry Draft.

Following his draft, he played for the North Dakota Fighting Sioux of the Western Collegiate Hockey Association (WCHA) for three seasons.[6] Scoring a team-leading 24 goals as a freshman, he added 21 assists for 45 points total. He also set a school record with nine game-winning goals in the season, which also led all NCAA players. He was named to the WCHA All-Rookie Team and the WCHA Final Five All-Tournament Team.[5]

In his sophomore year, he improved to 52 points (17 goals and 35 assists), ranking second in team scoring. He earned Third Team All-WCHA and received the Fighting Sioux's Cliff "Fido" Purpur Award, given to the player who demonstrates hard work, determination, while generating excitement on the ice. Following North Dakota's WCHA playoff run, Oshie led all players with eight points (four goals and four assists) in the 2006 NCAA Tournament, earning NCAA West All-Tournament honors. He played his last season with North Dakota as a junior, recording 45 points in 42 games.[5]

On May 13, 2008, Oshie opted to forgo his senior season with the University of North Dakota and signed with the St. Louis Blues.[7] He scored his first career NHL goal on October 22, 2008, against the Detroit Red Wings. Oshie quickly became a fan favorite due to his fast and energetic style of play. Playing in 57 games, Oshie collected 14 goals, 25 assists and 39 points during his rookie year. At the end of the season, he won the NHL's 2008–09 "Goal of the Year" honors, a fan-voted contests on the league's website. [8]

On January 1, 2014, Oshie was named to the United States' roster for the 2014 Winter Olympics along with St. Louis teammates David Backes and Kevin Shattenkirk.[10] Oshie was a player on the "bubble" as he was one of several American-born players being considered for one of Team USA's final roster spots. Oshie was eventually chosen because of his success rate in shootouts.[11] On February 15, in a preliminary-round game against Russia, Oshie was repeatedly selected by Team USA head coach Dan Bylsma to participate in a shootout against the Russian team that ultimately resulted in a 3–2 American victory.[12] Oshie was the first of three shooters to face Russian goalie Sergei Bobrovsky in the shootout, and was followed by teammates James van Riemsdyk and Joe Pavelski. After the score remained tied after the first three rounds, international rules stipulated that coaches could re-use players as often as desired. Oshie was subsequently tabbed by Bylsma five consecutive times, ultimately converting 4 of 6 shot attempts including the game winner in the 8th round of the shootout.[13][14][15]

Oshie is from the Anishinaabe or Ojibwe Nation; his name in Ojibwe language or Anishnaabemowin, "Keeway Gaaboo" means "Coming Home".[17] Giiwe translates roughly as s/he returns home. If the -aaboo in Gaaboo refers to water, then this name may evoke the poetic image of water that, by traveling downhill inevitably will find its way home to a larger body of water such as the Great Lakes or the sea. His father is Anishnaabe.[18]